Press feeder control apparatus

ABSTRACT

In a press feeder control a main counter is provided for initially manifesting a quantity representative of the distance travelled by a web as it is drawn into position in relation to a press, and decremented in response to each incremental movement of such web, so that it is decreased to zero as the web is moved to the proper position. The drive of the web is controlled to accelerate the web at a preselected rate until a preselected velocity is obtained, and to decelerate the web at the same preselected rate so as to bring the web to the desired position as the velocity of the web is reduced to zero. Means is provided for selectively driving the out-feed drive at a faster rate than the in-feed drive, to stretch the web in the vicinty of the press.

United States Patent [1 1 Sommeria June 3, 1975 PRESS FEEDER CONTROL APPARATUS Primary Examiner-Richard A. Schacher 7 l t M l 5] men or R Sommena Palos Heights Attorney, Agent, or Firml-l1ll, Gross, S1mpson, Van

Santen, Steadman, Chiara & Simpson [73] Assignee: Hyper-Loop, Inc., Bridgeview, Ill. [22] Filed: Jan. 2, 1973 57 ABSTRACT [21] Appl' 3201272 In a press feeder control a main counter is provided for initially manifesting a quantity representative of 52 US. (:1. 226/136; 226/139; 318/603; the distance travelled y a Web as it is drawn into p 31 5; 313 9 tion in relation to a press, and decremented in re- [51] Int. Cl B6Sh 17/22 sponse to each incremental movement of Such 80 [58] Fi f S h 0 22 134 13 137 139 that it is decreased to zero as the web is moved to the 22 33 43; 3 9 5 00 0 03 proper position. The drive of the web is controlled to accelerate the web at a preselected rate until a prese- [56] References Cited lected velocity is obtained, and to decelerate the web UNITED STATES PATENTS at the same preselected rate so as to bring the web to the desired position as the velocity of the web is rem g duced to zero. Means is provided for selectively driv- 3458787 7/1969 i "M81603 x ing the out-feed drive at a faster rate than the in-feed 3:466:517 9/1969 318/696 x drive, to stretch the web in the vicinty of the press. 3,579,279 5/1971 lnaba 3l8/696 3,599,068 3/1971 Kanamori 318/603 14 Clam, 7 Draw led/ 4F 23 .55 5 a k4/WP MA/A/ Z CK CZ??? [am/75k COUNTER 36 7 4o caM/M/me I EEPET/T/VE a /ii'i a Awe c "om/me '38 J4 l/V-FL-ZD I,- 47 4, F37 DRIVE P/c's 7a car L061: cou/vrca L our 57K arc/l our-F550 7km! z 0 an: OR/VE PRESS FEEDER CONTROL APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to control apparatus for a punch press or the like, and more particularly to digital apparatus by which the feed of the web to the press, and away from the press, may be accurately controlled for maximum speed and accuracy in the positioning of the web.

2. The Prior Art It is important to correctly position a web formed a sheet metal or the like in relation to a punch press or the like when a quantity of similar shapes are to be punched from the web. In order to maintain efficient use of the material in the web, the web must be positioned accurately so as to produce a minimum amount of wastage in between adjacent punched sections of the web. At the same time, in order to improve efficiency of operation of the press, the web must be correctly psitioned as rapidly as possible. It has not been possible in the past to achieve accurate positioning without sacrificing some speed of operation, and vice versa.

In the prior art it has been customary to employ analog type devices, or hybrid digital-analog devices for feeding the web into correct position in relation to the press. However, the analog devices and the analog portions of the hybrid devices are subject to long-time drift and do not insure maximum accuracy over long periods of time. Moreover, as they are responsive to the magni' tude of the difference between the desired position and the actual position at any given time, the speed of operation is quite low if high accuracy is desired.

SUMMARY OF THE INVENTION It is a principal object of the present invention to provide a press feeder control apparatus which is adapted for rapidly and accurate positioning of a web in relation to rapid punch press or the like.

Another object of the present invention is to provide such apparatus which operates by entirely digital means.

A further object of the present invention is to provide means for electronically synchronizing the in-feed and the out-feed of the web in relation to the press.

Another object of the present invention is to provide press feeder control apparatus by which the out-feed may be made more rapid than the in-feed of the web, to allow for stretching of the web material.

A further object of the present invention is to provide press feeder control apparatus in which the maximum velocity and the rate of acceleration and deceleration are independently selectable without affecting accuracy of the positioning.

Another object of the present invention is to provide press feeder control apparatus in which the time at which deceleration is to be initiated is computed automatically so as to permit the deceleration of the web to terminate exactly at the time that the web reaches its correct position.

These and other objects and advantages of the present invention will become manifest upon an inspection of the following description and the accompanying drawings.

In one embodiment of the present invention there is provided a main counter, means for presetting the main counter with a quantity representative of the length of feed desired for a quantity of web material, means for decrementing the main counter at an increasing rate until a maximum rate is achieved, means for accelerating the web material in response to the rate at which the main counter is counted down, a second counter, means for incrementing the second counter until equality is reached, between the quantity manifested in the main counter and the quantity manifested in the second counter, and means responsive to such equality for decreasing the speed at which the main counter is decremented, whereby said counting rate is reduced to zero and the main counter is reduced to zero, simultaneously with the web material having been advanced by the length represented by the initial quantity inserted into the main counter.

BRIEF DESCRIPTION OF THE DRAWINGS Reference will now be made to the accompanying drawings in which:

FIG. 1 is a functional block diagram of a system incorporating an illustrative embodiment of the present invention;

FIG. 2 is a functional block diagram showing certain portions of FIG. I in more detail;

FIG. 3 is a functional block diagram of the stretch logic unit of FIG. 1;

FIG. 4 is a functional block diagram of the main counter illustrated in FIG. I; and

FIGS. 5-7 are graphs illustrating the operation of the apparatus under various conditions.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference will first be made to FIG. 5, which illustrates graphs of certain parameters of the web material as it is fed to the press. The curve 10 shows the velocity of the web with respect to time. It can be seen that the velocity increases linearly from zero until a maximum value VM is reached at time 11, after which the maximum velocity is maintained until time t2. At 12, the velocity is reduced in a linear fashion until zero velocity is reached at time :3. As more fully described hereinafter, the maximum velocity of the web VM is controlled in accordance with a preselected value, and the constant acceleration between zero and :1, which is equal to the constant deceleration between :2 and I3, is also a preselected value.

A main counter controls the distance for which the web is fed during each cycle of operation of the apparatus. The content of the main counter is illustrated in FIG. 5 with respect to time on the time scale as the curve 12. The curve 12, which represents the content of the main counter, decreases from a predetermined initial value L, which is preset into the main counter in proportion to the distance desired for the web to be fed as it is fed in toward the press. During the time that the velocity of the web is increasing, the content of the main counter is decreased parabolically downward, after which the content of the main counter is decreased at a constant rate for the period between t1 and :2. At :2 the content of the main counter is decreased more gradually (parabolically) until it reaches zero at the same time that the velocity of the web is reduced to zero.

FIG. 5 also illustrates a graph which corresponds to the content of a second counter, hereinafter sometimes referred to as an up-counter. The content of the upcounter increases parabolically from zero until t1, when the velocity VM of the web is reached, after which the content of the up-counter is maintained at a constant value until 22, during which the web travels at a constant maximum velocity. At the end of this period the content of the up-counter is reduced parabolically to zero, reaching zero at the time that the web velocity is reduced to zero. The function of the up-counter is to determine when the time 12 occurs, at which the content of the up-counter is equal to the content of the main counter, and which signifies that deceleration of the web, at the same rate at which it was accelerated prior to :1, is to begin so as to reduce the velocity of the web to zero at the same time it arrives at its desired position.

FIG. 5 illustrates in dashed lines the operation of the present invention for a smaller predetermined distance L. The main counter begins to decrease its content in the same manner described for the distance L, as shown by the curve 16, and the up-counter begins to count upwardly at the same rate as before. As soon as the contents of the main counter and the up-counter are equal, however, the main counter slows its rate of decrease, and the velocity, shown in curve 18, also decreases, reducing the velocity to zero as the content of the main counter reaches zero.

FIG. 1 illustrates a clock pulse generator 20, which furnishes clock pulses for operating a ramp time control device 21, which is controlled in accordance with the setting of a manual control device 22, to produce a variable frequency train of pulses on an output line 23, which is connected to the input of a ramp counter 24. The counter 24 is employed for the purpose of generating the curve of FIG. 5, and the velocity of the web is proportional to the content of the counter 24.

The clock pulse generator is also connected to a feed speed control device 25, which is controlled by the manually adjustable device 26 to produce an output pulse train on a line 27 proportional to the maximum desired velocity of the web. Accordingly, the device 26 establishes the proportionality factor between the content of the counter 24 and the velocity of the web. The line 27 is connected to the input of a repetitive adder 28, which produces a pulse train on an output line 29, proportional to the product of the pulse repetition rate of the pulse train on the line 27, and the content of the counter 24. The pulses on the line 29 control the infeed drive, and are furnished to the drive via a logic unit 30 to a line 31 connected to the in-feed drive unit 32. The drive unit 32 may be any type which is responsive to a train of pulses for moving a member an incremental length for each such pulse. One such unit is described in my copending application, Ser. No. 266,579 filed June 27, [972 for Digital Regulating Control For Servo System."

The pulses on the line 29 are also fed to the main counter 33 and to the up-counter 34. The main counter 33 is initially set to a quantity representative of the desired distance the web is to move, by signals over a line 35 from a terminal 36. The tip-counter is initially preset to zero by a signal over a line 37 from the logic unit 30.

The ramp counter 24 is counted to its maximum capacity, which is 15, and then sends a signal to the logic unit 30 over a line 38, which causes the logic unit to disconnect the counter 24 from the ramp speed time control unit 21 (by means not shown) so that the counter 24 continues to manifest its maximum count, for controlling the web to move at maximum speed.

When the contents of the main counter 33 and the up-counter 34 become equal, this is recognized by a comparator unit 39, which furnishes a signal to the logic unit 30 over a line 40. The logic unit then reconnects the counter 24 to the unit 21, but in such a way that the counter 24 is decremented by pulses from the unit 21, so as to gradually reduce the speed of the web. When the counter 24 is reduced to its zero, a pulse is produced on a line 41, connected to the logic unit 30. Simultaneously, the content of the main counter 33 is reduced to zero, and a pulse is conveyed to the logic unit 30 over a line 42, and the logic unit 30 discontinues emitting pulses on the line 31.

The outfeed drive 43 is preferably the same as the infeed drive 32, and is controlled by the logic unit with a pulse train over the line 31 connected to the outfeed drive 43 through a stretch logic unit 44. The logic unit 44 is controlled by a manually adjustable device 45 to add pulses to the pulse train on the line 31 at a predetermined rate, so as to increase the pulse repetition rate applied to the outfeed drive 43, and stretch the web material in the vicinity of the press as desired.

A counter 46 is provided for controlling the number of cycles of operation of the apparatus. It is initially preset by a signal from a terminal 46' over a line 47, to the numbers of cycles desired, and disables the logic unit 30 over a line 48 when the desired number of cycles have been performed.

Referring now to FIG. 2, some of the apparatus of FIG. 1 is illustrated in more detail. At the beginning of a cycle the main counter 33 is loaded with a quantity representative of the distance which the web is to be moved for correct positioning of the web in relation to the press by means of switches 49. A start feed signal is produced at a terminal 50 when the web is to be fed by the distance preset into the counter 33. A line 51 is connected from the terminal 50 to the input of a switch noise suppressor unit 52, which functions to suppress the noise on the line 51 by clipping or the like, producing on an output line 53 a pulse which is substantially free of noise. The line 53 is connected to the input of a line receiver 54 which produces a pulse at its output which is at the correct voltage level for the logic units which follow. The output of the line receiver 54 is connected to the D input of a flip-flop 55, to set the flipfiop 55.

The clock input of the flip-flop 55 is connected to a terminal 56 which is supplied with ramp frequency pulses from the ramp time control unit 21 (FIG. 1). The ramp frequency pulses cause the flip-flop 55 to be reset with the next pulse following its setting but in the meantime the flip-flop S5 is effective to produce a pulse on an output line 57, which is connected to the input of a monostable multivibrator 58. The output of the monostable multivibrator 58 is connected to the input of a second monostable multivibrator 59, and the output of the multivibrator 59 is connected to one input of a NAND gate 60. The two monostable multivibrators 58 and 59 insure against incorrect operation which would result if a second start feed pulse was presented to the terminal 50 before the cycle is completed.

The output of the multivibrator 58 is connected to one input of a NAND gate 61. The other input to the gate 61 is connected from the 0 output of a flip-flop 62, which is initially in its reset state, thus disabling the gate 61. The output of the multivibrator 59, which occurs later, is connected through the gate 60 to place the flip-flop 62 in its set state, thus enabling the gate 61. However, by this time, the output from the multivibrator 58 has ceased, so the gate 61 remains non functional. If a second pulse is applied to the terminal 50 while the flip-flop 62 is set, the gate 61 passes a pulse from the multivibrator 58 to set a flip-flop 63, to signify a feed error. When the flip-flop 63 is set, a signal is supplied to the error control apparatus 63a, which functions to disable operation of the apparatus as long as an error persists. lt furnishes a signal which resets the flipflop 63 when an error condition is corrected.

The NAND gate 60 has two inputs in addition to the one connected from the multivibrator 59. One of these inputs is supplied from the counter 46 over a line 64, and the signal on this input is high as long as the number of cycles manifested by the counter 46 has not been reached. The counter 46 is preset initially with the number of cycles to be performed by signals from the input terminal 46' and is decremented by unity for each cycle over a line 66.

The other input to the gate 60 is connected from a terminal 67 which is high when the apparatus is to operate in an automatic mode. The Q output of the flipflop 62 is connected to one input of a NAND gate 68, and enables the NAND gate 68 to pass command pulses present on a line 69 to the output thereof and through an inverter 70 to the input of the main counter 33. Another terminal of the NAND gate 68 is connected to the output of the error control unit 630 over a line 70 so that the gate 68 is inhibited when an error has occured. Another input to the gate 68 is connected to a terminal 71, which is normally high. The level at the terminal 71 goes low in response to manula operation of a switch when it is desired to inhibit operation of the apparatus.

The pulses which are passed by the gate 68 are effective to decrement the main counter 33.

The output of the gate 68 is also connected over a line 72 and through a NAND gate 73 to the input of the up-counter 34, so that the up-counter 34 counts upwardly from zero at the same rate that the content of the main counter 33 is being decreased. The NAND gate 73 is enabled by a line 74 which is connected from the output of a NAND gate 75. The output of the NAND gate 75 is connected to the line 74 through an inverter 76.

The output of the NAND gate 75 is low when a flipflop 77 is in its set state, and two other flip-flops 78 and 79 are in their reset states, a condition which occurs for the first time when the flip-flop 77 is set by a signal over a line 80 from the NAND gate 60 at the same time that the flip-flop 62 is set. The other two flip-flops 78 and 79 which control the NAND gate 75 have previously been preset, as had the flip-flop 77, over a line 81. Accordingly, the NAND gate 73 is enabled to pass command pulses over the line 82 to increment the counter 34 at the same rate that the main counter 33 is being decremented.

The output of the inverter 76 is also connected to a line 82 which is connected to one input of a NAND gate 83. The other input of the NAND gate 83 is connected to the terminal 56, which furnishes the pulses at the ramp frequency, so that pulses are passed by the gate 83, to the ramp counter 24, which has preligusly been cleared over a line 84 connected from the 0 out- 6 put of the flip-flop 62, which occurs at the time that the flip-flop 62 is preset by the signal derived from the NAND gate 60.

The counter 24 is connected in association with the repetitive adder 28, which adds the content of the counter 24 over and over, once for each pulse applied thereto over a line 85 from a terminal 86, which terminal is connected to the feed speed control unit 25 (FIG. 1). The storage capacity of the adder 28 is exceeded periodically, as the content of the counter 24 is added frequently by the adder unit 28, and each time the capacity is exceeded, an overflow pulse is produced on the line 29. The pulse train thus produced has a pulse repetition rate corresponding to the quantity stored in the counter 24, since the larger is the quantity stored in the counter 24, the fewer times that that quantity must be added to exceed the capacity of the adder 28. The overflow pulses are conveyed to a NAND gate 68 over the lines 29 and 69 and then to the counters 33 and 34. The initial count in the counter 24 is zero, as it is cleared by the pulse on the line 84. However, the pulses which are supplied to the counter 24 through the gate 83 cause its content to increase, resulting in an increase in frequency of overflow pulses on the line 29. Therefore, the rate at which the main counter 33 is being decreased, and the rate at which the up-counter 34 is being increased, increases in proportion to the quantity stored in the counter 24. This rate is also proportional to the pulse repetition rate of the pulse train on the line 85, for this determines the rate at which the content of the counter 24 is added.

When the quantity stored in the counter 24 reaches l5," this is recognized by a unit 87, which produces a pulse on the line 38. The counter 24 is a four stage binary counter, so that the quantity 15" is identified by high outputs from all four stages of the counter. The unit 87 preferably contains a four input NAND gate connected to the four outputs of the counter 24, so that an output pulse is produced on the line 38 when all four outputs are high. The line 38 is connected to the set input of the flip-flop 78. Accordingly the flip-flop 78 is set, and its Q output goes low, thereby disabling the NAND gate 75, and disabling the gate 73 by which command pulses are supplied to the up-counter 34. Accordingly, no further pulses are introduced into the upcounter 34, which therefore maintains the count which it manifests at the time that the counter 24 reaches 15.

The quantity l5," when stored in the counter 24 gives a maximum frequency of overflow pulses on the line 29, which is proportional to the repetition rate of the pulses applied to the terminal 56, with the result that the frequency of the command pulses applied to the counters 33 and 34 is at a maximum. As the command pulses represent individual increments of movement for the web, as it is fed in toward the press, the frequency at which the command pulses are produced is directly proportional to the velocity of the web. As a result, the velocity of the web is increased to a maximum and that maximum is realized when the counter 24 reaches the quantity l5." Thereafter, feed continues with the content of the main counter 33 being reduced at a constant rate, until a comparison between the quantities stored in the main counter 33 and the upcounter 34 is recognized by the comparator unit 39. When this occurs an output pulse is produced on the line 40, which is effective to change the state of the flipflop 79, as the li ne 40 is connected to its clock input. This causes the Q output of the flip-flop 79 to go low, disabling the NAND gate 75 if it is not already disabled, and produces an output signal on the Q output of the flip-flop 79. The line 102 is connected from the output of the flip-flop 79 to one input of a NAND gate 103, the other input of which is connected to the terminal 56 to receive the pulses at the ramp frequency. Accordingly the gate 103 passes the pulses from the terminal S6 to a line 104 which is connected to the reverse counting input of the counter 24. Accordingly, the counter 24 is decremented by application of successive pulses from the terminal 56 over the line 104, with the result that the frequency of the overflow pulses produced on the line 29 is reduced, thereby decelerating the web.

This operation continues, with additional pulses being supplied to decrease the quantity stored in the counter 24, until the counter 24 has been reduced to zero. This occurs at the same instant at which the main counter 33 is reduced to zero, for the time required to reduce the counter 24 from l to zero, by application of the pulses at the terminal 56, is the same time which is required to increase it from zero to l5," and that time corresponds to the time required to produce the number of command pulses stored in the upcounter 24. This is exactly the same number of pulses which remain in the down counter at the time that the comparator unit 59 issues its output pulse on the line 40. Accordingly, the velocity of the web, which is proportional to the quantity stored in the counter 24, is reduced to zero at the same time at which it reaches its correct position in relation to the press, having moved the number of increments of movement initially set into the main counter 33.

A monostable multivibrator 106 is connected to the line 41, which produces a pulse when the content of the counter 24 is reduced to zero. The pulse causes the multivibrator 106 to emit a pulse on an output line 81, which is connected to the reset inputs of the flip-flops 77, 78 and 79, thus serving to reset them to their initial conditions. The resetting of the flip-flop 79 causes the output on the line 102 to go low, disabling the gate 103, so the counter 24 is held at zero. The multivibrator 106 is also triggered by a pulse appearing on a line 111, which is developed when the content of the main counter 33 reaches zero.

The line 42 is connected to one input of a NAND gate 107, the two other inputs of which are normally high. One of these inputs is connected to a terminal 108, which goes low momentarily when power is first applied to the system, and the other is connected to a terminal 109, which goes low momentarily when the apparatus is desired to be reset for any reason.

The output of the gate 107 is connected through an inverter 110 to a line 111, which is connected to an input of the multivibrator 106, and also to the reset input of flip-flop 62, which serves to reset the counter 24 to zero, via the line 84, and to decrement the batch counter 65 by means of a pulse transmitted thereto over the line 66. The Q output goes low, which serves to disable the gate 68. The aoutput of the flip-flop 62 is also connected over a line 112, through an inverter 113, to an input 114 of the up-counter 34, which operates to reset the up-counter to zero, and to an input 1 of the main counter 33, which serves to transfer a new quantity into the counter 33 from the switches 49, preparatory to a new cycle of operation.

The command pulses are supplied to the in-feed drive from the gate 68 by means of NAND gates 116 and 117. One input of the NAND gate 116 is connected to the output of the gate 68, via the line 82, to receive the pulses applied to the main counter 33, and its second input is enabled when a flip-flop 118 is in condition to select an automatic mode of operation. This produces a signal on an output line 119 which is connected to one input of the NAND gate 117. The other input of the NAND gate 117 is connected to a terminal 120 which is normally high, except when a jogging operation is desired. The output of the NAND gate 117, which is supplied to the line 31, is then supplied to the in-feed drive, which feeds the material from its source of supply into proper position in relation to the press.

Two additional NAND gates 121 and 122 are provided for the out-feed drive, and they correspond generally to the gates 116 and 117 for the in-feed drive. The gate 121 however, instead of being connected to the source of command pulses produced at the output of the gate 68, is instead connected to a terminal 123, to which a train of pulses is applied which will be referred to as mixed" pulses. The mixed pulses comprise the command pulses produced at the output of a NAND gate 68, but, in addition, also include the pulses produced in response to the operation of the stretch logic 44, which is activated when it is desired to stretch the web material in the vicinity of the press. When this is desired, additional pulses are fed to the out-feed drive to cause it to function at a slightly greater velocity than the in-feed drive. The second input of the gate 121 is connected to the 0 output of the flip-flop 118, which is high in the automatic mode, and its output is connected to an input of the gate 122. The second input of the gate 122 is connected to the terminal 120, which is normally high, and its output is connected to the out-feed drive over a line 124.

The source of the mixed pulses applied to the terminal 123 is shown in FIG. 3.

The output of the NAND gate 68 is connected by way of a line 128 and an inverter 130 to one input of a NAND gate 131, and the source of stretching pulses is connected to the other input of the NAND gate 131. The frequency of stretching pulses is selected by means of a plurality of manually operable switches 132, which are connected via gates 134 to four repetitive adding units l35a-135d, connected to function as a 16 stage repetitive adder. Four switches 132 are provided, and they are connected to four successive ones of the 16 inputs of the repetitive adder 135a-135d. The inputs which are thus connected are selected by the gates 134, so that a great range of quantities may be represented by the four switches 132.

A flip-flop 131 has its input connected to the output of the inverter 130, so that it changes its state for every command pulse applied thereto over the line 128. A NAND gate has one input connected to the overflow output of the fourth stage 135d of the repetitive adder, and another input connected to the line 138, so that the pulses produced on the line 136 are synchronized with the pulses applied to the line 128, and have a pulse repetition rate which is a submultiple of the rate of the pulses on the line 128, as controlled by the switches 132. Four switches 132 are provided, which operate to preset four successive stages of the multistage counter 134, which is preferably 16 stages. The selection of the stages to which the switches 132 are connected is made in accordance with the range of stretching which is desired. The repetitive adder 135a-135d functions to produce at an output line 136 an output pulse train having a pulse repetition rate proportional to the product ofthe quantity represented by the switches 132, and the pulse repetition rate of pulses applied to the operating inputs of the adder units 1350-135d over the lines 137 and 138 from a flip-flop 139. The output of the gate 140, at which the stretching pulses are produced, is connected through two monostable multivibrators 142 and 144 in succession to a second input of the NAND gate 131. The output of the second monostable multivibrator 144 effectively disables the NAND gate 131 during the middle portion of one of the command pulses supplied from the inverter 130, but restores it to its ordinary mode of operation before the end of such command pulse, to in effect, transform a single command pulse on the line 128 into a pair of command pulses. The result is that an additional pulse is added to the terminal 123 for each pulse passed by the gate 140. The time period of the first multivibrator 142 is sufficient to delay the pulse from the gate 140 so that its leading edge occurs about onethird pulse time after the leading edge of a pulse produced by the inverter 130, and the time period of the multivibrator 144 is sufficient to cause the pulse applied to the gate 131 to disable it for only the middle third of one command pulse.

The amount of stretching of the web material in the vicinity of the press is controlled by the rate at which stretching pulses are produced at the output of the gate 140. As this is a submultiple of the command pulse rate, the stretching is constant for any rate of feed.

FIG. 4 illustrates the counter 24 with its three inputs 83a, 104 and 84. The input 84 functions to reset the counter 24, while the inputs 83a and 104 are connected, respectively, from the gates 83 and 103, serving to increment and decrement the counter 24 for each input pulse applied thereto. The repetitive addition unit connected to the counter comprises, in the embodiment shown in FIG. 4, three functional units 145, 146 and 147, which are commercially available integrated circuits. In one embodiment, the unit 145 is marketed by Texas Instruments under model No. SN 7483N, and the units 146 and 147 are marketed by Signetics under model No. N828OA. The manner in which these units are connected to form a repetitive adder is well known. The drive for the adder is derived from the terminal 86 and is connected directly to the unit 147 over the line 85, and to the unit 146 through an inverter 148, so that the units 146 and 147 are alternately energized in response to a pulse train arriving at the terminal 86. A NAND gate 149 has one input connected to an output of the unit 145 and the other is connected to the line 85, so that output pulses produced thereby are synchronized with the incoming pulse train.

The repetitive adders employed for the stretch logic unit shown in FIG. 3 are formed of the same components, but the units corresponding to the unit 145 of FIG. 4 are connected together in cascade, to accommo date a wider range of output pulse repetition rates.

Preferably, the ramp time control unit 21 and the feed speed control unit 25 are also formed in the same manner as the arrangement of FIG. 4, except that groups of switches 22 and 26 are substituted for the counter 24 in FIG. 4, so that the pulse repetition rate of the output pulse train is a product of the pulse repetition rate of the clock pulse generator 20, and the quantity manually set into the switches 22 and 26.

In an alternative embodiment of the present invention, all of the repetitive adder units are replaced by another form of multiplier unit, which functions to produce an output pulse train having a pulse repetition rate proportional to the product of the pulse repetition rate of an input pulse train, and the content ofa register such as the counter 24 or a group of switches. One such multiplier which may be employed in substitution for the repetitive adders used in the embodiment described above is marketed by Texas Instruments under model No. SN 7497, and its use as a multiplier is described in the Ti. Application Note CAl60.

The effects of modifying the multiplier employed in the units 21 and 25 are shown in FIGS. 6 and 7. FIG. 6 shows velocity curves for the web for two different settings of the switches 26, which control the pulse repetition rate on the line 27. The time positions of the times :1, t2, and :3 are unchanged, but the maximum web velocity has been altered.

FIG. 7 shows velocity curves for two different settings of the switches 22, which control the pulse repetition rate on the line 23. The maximum velocity is constant, but the rate employed for acceleration and deceleration is altered. For any settings of the switches 22 and 26, however, synchronization is maintained, and the velocity of the web is brought to zero as the web arrives at its proper position.

The provision by which the gate is disabled by the setting of either of the flip-flops 78 and 79 enables the apparatus to operate properly for any distance L set into the main counter 33. If the distance L is relatively large, the gate 75 is disabled when the counter 24 reaches l5." Otherwise, it is disabled when the upcounter 34 reaches the same count as the main counter 33, the condition illustrated by the dashed curve 16 in FIG. 5.

In order to insure that the content of the main counter 33 is reduced to zero during the cycle, even if the counter 24 reaches zero before the main counter 33, the adder unit 28 has its carry-in input 160 connected to a source of positive potential at a terminal 161, so that an output is present on the output of unit (FIG. 4) after the counter 24 reaches zero. This operates to cause the adder 28 to add unity to the content of the adder 28 for each pulse at the terminal 86, so that overflow pulses are produced at a low rate, even when the counter 24 is zero. These are passed to the gate 68. The counter 33 is thereby positively reduced to zero, and the resetting of the flip-flop 62 disables the gate 68. This operation positively brings the main counter 33 to zero to avoid a hang-up which otherwise would prevent the drive from reaching the desired position.

Although manually operated switches 22, 26, 132 and 49 have been described in connection with the apparatus illustrated in the drawings, such switches may optionally be replaced with a register or the like, set in accordance with signals produced by a card reader, magnetic tape reader, or the like, or an input from a computer.

The inverter 148 is employed in the apparatus of FIG. 4 to derive staggered control pulses for controlling the units 146 and 147. lt is preferable to employ a flipflop with the repetitive adder units associated with the ramp time control 21 and the feed speed control 25, with the flip-flop connected to c hange its state with each input pulse, and the Q and Q outputs of the flipflop connected to control the units similar to the units 146 and 147 of FIG. 4.

It will be appreciated that although the present invention has been described specifically in terms of a press feeder, it may be employed wherever precise and swift movement is desired. The invention is especially useful where it is desired to independently select desired values for velocity and acceleration.

In one embodiment, the following devices were employed for some of the functional units illustrated in the drawings:

Counter 24 T.l. model SN 74I93N Counter 33 four Tvl. model SN 74l93N units Counter 34 four Signetics model N828lA units Comparator 39 four Tl model SN 74L85M units Adder 145 T.l. model SN 483N Units l46 & 147 T.l. model SN 8280 NAND gates T.l. model SN 7400M Flip-flops T,l. model 7474N Monostuble Multivibrators Tl model 74l22N What is claimed is:

1. In apparatus for controlling the movement of a member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train having a manually adjustable pulse repetition rate, means for connecting said pulse train to said main counter for decrementing said counter with each pulse of said pulse train, and means adapted for connecting said pulse train with said drive means, said generating means including means for varying the pulse repetition rate of said pulse train, decreasing said pulse repetition rate to substantially zero when said member reaches said second position.

2. Apparatus according to claim 1 wherein said generating means includes means for increasing the pulse repetition rate of said pulse train from zero to maxi' mum value as said member moves from said first position, and means for decreasing said pulse repetition rate from said maximum value to zero as said member reaches said second position, the rate of decrease of the pulse repetition rate being equal to the rate of increase of the pulse repetition rate.

3. Apparatus according to claim 2 including a second counter, means for connecting said pulse train to said second counter during the period in which the pulse repetition rate of said pulse train is increasing to a maximum value, and thereafter manifesting the number of pulses counted by said second counter while said pulse repetition rate is maintained at said maximum value.

4. Apparatus according to claim 3 including a comparator connected to said main counter and to said second counter and responsive to a coincidence between the content of said main counter and said second counter to produce an output signal, and means connected to said comparator and responsive to said output signal for intiating a decrease in the pulse repetition rate of said pulse train.

5. Apparatus according to claim 1 including connecting means for interconnecting said train of pulses with said drive means, said connecting means being adapted to selectively insert additional pulses into said pulse train.

6. Apparatus according to claim 5 including manually operable means for selecting the frequency of pulses inserted into said pulse train.

7. ln apparatus for controlling the movement of a member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train, means for connecting said pulse train to said main counter for decrementing said counter with each pulse of said pulse train, means adapted for connecting said pulse train with said drive means, said generating means including means for varying the pulse repetition rate of said pulse train, increasing said pulse repetition rate from zero to a maximum value as said member moves from said first position, and decreasing said pulse repetition rate from said maximum value to zero as said member reaches said second position, the rate of decrease of said pulse repetition rate being equal to the rate of increase of said pulse repetition rate, a second counter, means for connecting said pulse train to said second counter during the period in which the pulse repetition rate of said pulse train is increasing to a maximum value, and thereafter manifesting the number of pulses counted by said second counter while pulse repetition rate is maintained at said maximum value, a comparator connected to said main counter and to second counter and responsive to a coincidence between the content of said main counter and said second counter to produce an output signal, means connected to said comparator and responsive to said output signal for initiating a decrease in the pulse repetition rate of said pulse train, a third counter, means for generating said pulse train having a pulse repetition rate proportional to the product of the content of said third counter and the pulse repetition rate of an input pulse train, means for increasing the content of said third counter as said member is moved from said first position, and means for decreasing the content of said third counter in response to the output signal from said comparator unit.

8. Apparatus according to claim 7 including a source of clock pulses, and adjustable means having a storage device, said adjustable means being connected to said source of clock pulses and adapted to produce a train of pulses having a pulse repetition rate proportional to the product of the pulse repetition rate of said clock pulse source and a quantity manifested in said storage device, and means for connecting said adjustable means with said second counter.

9. Apparatus according to claim 7 including a source of clock pulses, adjustable means having a storage device, said adjustable means being connected with said source of clock pulses and adapted to produce an output pulse train having a pulse repetition rate proportional to the product of the pulse repetition rate of said clock pulse source and a quantity means to said third counter for incrementing said counter from zero to a maximum value in response to each of the pulses produced by said adjustable means.

10. Apparatus according to claim 7 including means for increasing the content of said third counter at a uniform rate until a maximum content is reached. and means causing said third counter to manifest the number of pulses applied thereto during the period of increase of the pulse repetition rate of said pulse train.

11. In apparatus for controlling the movement of a member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train, means adapted for simultaneously connecting each pulse of said pulse train to said main counter for decrementing said counter and to said drive means for moving said memher, said generator means including means for varying the pulse repetition rate of said pulse train, increasing said pulse repetition rate as the first pulses of said pulse train are applied simultaneously to said main counter and to said drive means, and decreasing said pulse repetition rate to substantially zero when said member reaches said second position.

12. In apparatus for controlling the movement of the member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train, means for connecting said pulse train to said main counter for decrementing said counter with each pulse of said pulse train, means adapted for connecting said pulse train with said drive means, said generating means including means for varying the pulse repetition rate of said pulse train for the first group of pulses applied to said drive means as said member moves away from said first position and for decreasing said pulse repetition rate to substantially zero when said member reaches said second position and for maintaining said pulse repetition rate at a constant value between said first group of pulses and the period of decreasing pulse repetition rate, and manually operable means for selecting the value of said constant pulse repetition rate.

13. Apparatus according to claim 12, including manually operable means for selecting the length of the periods over which said pulse repetition rate is increasing and decreasing.

14. In apparatus for controlling the movement of a member from a first position to a second position including drive means operablein response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train, means for connecting said pulse train to said main counter for decrementing said counter with each pulse of said pulse train, and means adapted for connecting said pulse train with said drive means, said generating means including means for linearly varying the pulse repetition rate of said pulse train, decreasing said pulse repetition rate to substantially zero when said member reaches said second position. 

1. In apparatus for controlling the movement of a member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train having a manually adjustable pulse repetition rate, means for connecting said pulse train to said main counter for decrementing said counter with each pulse of said pulse train, and means adapted for connecting said pulse train with said drive means, said generating means including means for varying the pulse repetition rate of said pulse train, decreasing said pulse repetition rate to substantially zero when said member reaches said second position.
 1. In apparatus for controlling the movement of a member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train having a manually adjustable pulse repetition rate, means for connecting said pulse train to said main counter for decrementing said counter with each pulse of said pulse train, and means adapted for connecting said pulse train with said drive means, said generating means including means for varying the pulse repetition rate of said pulse train, decreasing said pulse repetition rate to substantially zero when said member reaches said second position.
 2. Apparatus according to claim 1 wherein said generating means includes means for increasing the pulse repetition rate of said pulse train from zero to maximum value as said member moves from said first position, and means for decreasing said pulse repetition rate from said maximum value to zero as said member reaches said second position, the rate of decrease of the pulse repetition rate being equal to the rate of increase of the pulse repetition rate.
 3. Apparatus according to claim 2 including a second counter, means for connecting said pulse train to said second counter during the period in which the pulse repetition rate of said pulse train is increasing to a maximum value, and thereafter manifesting the number of pulses counted by said second counter while said pulse repetition rate is maintained at said maximum value.
 4. Apparatus according to claim 3 including a comparator connected to said main counter and to said second counter and responsive to a coincidence between the content of said main counter and said second counter to produce an output signal, and means connected to said comparator and responsive to said output signal for intiating a decrease in the pulse repetition rate of said pulse train.
 5. Apparatus according to claim 1 including connecting means for interconnecting said train of pulses with said drive means, said connecting means being adapted to selectively insert additional pulses into said pulse train.
 6. Apparatus according to claim 5 incluDing manually operable means for selecting the frequency of pulses inserted into said pulse train.
 7. In apparatus for controlling the movement of a member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train, means for connecting said pulse train to said main counter for decrementing said counter with each pulse of said pulse train, means adapted for connecting said pulse train with said drive means, said generating means including means for varying the pulse repetition rate of said pulse train, increasing said pulse repetition rate from zero to a maximum value as said member moves from said first position, and decreasing said pulse repetition rate from said maximum value to zero as said member reaches said second position, the rate of decrease of said pulse repetition rate being equal to the rate of increase of said pulse repetition rate, a second counter, means for connecting said pulse train to said second counter during the period in which the pulse repetition rate of said pulse train is increasing to a maximum value, and thereafter manifesting the number of pulses counted by said second counter while pulse repetition rate is maintained at said maximum value, a comparator connected to said main counter and to second counter and responsive to a coincidence between the content of said main counter and said second counter to produce an output signal, means connected to said comparator and responsive to said output signal for initiating a decrease in the pulse repetition rate of said pulse train, a third counter, means for generating said pulse train having a pulse repetition rate proportional to the product of the content of said third counter and the pulse repetition rate of an input pulse train, means for increasing the content of said third counter as said member is moved from said first position, and means for decreasing the content of said third counter in response to the output signal from said comparator unit.
 8. Apparatus according to claim 7 including a source of clock pulses, and adjustable means having a storage device, said adjustable means being connected to said source of clock pulses and adapted to produce a train of pulses having a pulse repetition rate proportional to the product of the pulse repetition rate of said clock pulse source and a quantity manifested in said storage device, and means for connecting said adjustable means with said second counter.
 9. Apparatus according to claim 7 including a source of clock pulses, adjustable means having a storage device, said adjustable means being connected with said source of clock pulses and adapted to produce an output pulse train having a pulse repetition rate proportional to the product of the pulse repetition rate of said clock pulse source and a quantity means to said third counter for incrementing said counter from zero to a maximum value in response to each of the pulses produced by said adjustable means.
 10. Apparatus according to claim 7 including means for increasing the content of said third counter at a uniform rate until a maximum content is reached, and means causing said third counter to manifest the number of pulses applied thereto during the period of increase of the pulse repetition rate of said pulse train.
 11. In apparatus for controlling the movement of a member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating A pulse train, means adapted for simultaneously connecting each pulse of said pulse train to said main counter for decrementing said counter and to said drive means for moving said member, said generator means including means for varying the pulse repetition rate of said pulse train, increasing said pulse repetition rate as the first pulses of said pulse train are applied simultaneously to said main counter and to said drive means, and decreasing said pulse repetition rate to substantially zero when said member reaches said second position.
 12. In apparatus for controlling the movement of the member from a first position to a second position including drive means operable in response to a train of pulses having a separate pulse for each increment of movement of said member, the combination comprising: a main counter, means presetting said main counter to manifest a quantity proportional to the distance between said first and second positions, generating means for generating a pulse train, means for connecting said pulse train to said main counter for decrementing said counter with each pulse of said pulse train, means adapted for connecting said pulse train with said drive means, said generating means including means for varying the pulse repetition rate of said pulse train for the first group of pulses applied to said drive means as said member moves away from said first position and for decreasing said pulse repetition rate to substantially zero when said member reaches said second position and for maintaining said pulse repetition rate at a constant value between said first group of pulses and the period of decreasing pulse repetition rate, and manually operable means for selecting the value of said constant pulse repetition rate.
 13. Apparatus according to claim 12, including manually operable means for selecting the length of the periods over which said pulse repetition rate is increasing and decreasing. 